A double blind clinical trial of lithium versus placebo is being conducted in 16-21 year-old males in a correctional institution. In the context of the ongoing research, these objectives may be particularized as follows: 1. To determine if lithium treatment reduces/modifies aggressivity and impulsivity and if so, whether and how these changes are integrated into the personality and institutional behavior of the subjects. 2. a) To exaeine the aggressive behavior of the subjects in terms of their familial, interpersonal, medical, and psychiatric histories; b) To examine the relationship between aggression and impulsivity; c) To determine the subject's attitude toward his aggressivity and to hypothesize the needs it fulfills and the role it plays in his personality.